Owen Paterson, the environment secretary, explained his opposition to equal marriage on the grounds that 'biddies don't like botties'. Photograph: Yui Mok/PA

Male Conservative MPs voted against equal marriage in larger numbers proportionally than their female colleagues, according to a breakdown of the voting figures after the historic debate in parliament.

The analysis of Tuesday's vote in favour of the change came as the most senior member of the cabinet to vote no was criticised for describing gay men as "botties".

Owen Paterson, the environment secretary who joined 136 Tory MPs in an unofficial rebellion, admitted on Sky News that he had explained his opposition to equal marriage on the grounds that "biddies don't like botties". Paterson said that he made the remarks, which were disclosed in the Mail on Sunday in December, at a private event. He told Sky News: "That is some private joke from many, many years ago which has been recirculated."

Asked why he opposed equal marriage, Paterson said: "This is an issue of conscience. There was a free vote. People expressed their views. The vote went through and the parliamentary procedure will take its place."

Ben Summerskill, chief executive of Stonewall, said Paterson's remarks spoke "volumes" about his opposition to the bill. "If that is the strongest opposition to equality gets then we are almost tempted to think we might be home and dry."

Paterson was criticised for his remarks as a breakdown of the voting figures in the Commons vote by the Guardian's Data Blog showed that 47% of male MPs voted against equal marriage compared with 30% of women. Of Tory MPs elected in 2010, 57% voted against the bill but among Tory MPs elected pre-2010 that figure was 60%.

In separate research the psephologist Phil Cowley tweeted that younger Conservative MPs were more likely to vote for equal marriage. Cowley tweeted: "Of those to vote (& excluding double votes), Con MPs born before 1970 split 45:55 against, those born 1970 or after split 58:42 in favour."

The research was published as the prime minister rejected calls to extend civil partnership to heterosexual couples on the grounds that it would weaken marriage. Cameron spoke out after Christopher Chope, the Tory MP for Christchurch, reiterated a demand made by traditionalist Tories in Tuesday's Commons debate by calling for heterosexual couples to be given the same rights as same-sex couples.

Chope asked Cameron in the first question at prime minister's questions: "Can [he] say, in response to the many concerns expressed in yesterday's debate, will he ensure that civil partnerships are open to heterosexual couples on an equal basis with homosexual couples?"

The prime minister replied: "I will obviously listen carefully to what he says. But frankly I am a marriage man, I am a great supporter of marriage. I want to promote marriage, defend marriage, encourage marriage.

"The great thing about last night's vote is that two gay people who love each other will now be able to get married. That is an important advance. I think we should be promoting marriage rather than looking at any other way of weakening it."

The prime minister spoke out after Francis Maude, the Cabinet Office minister who is seen as the founding father of Tory modernisation, said the vote on gay marriage showed that many Conservatives were slow to accept social change.

The equal marriage bill was given an overwhelming second reading by 400 votes to 175, a majority of 225. But the prime minister failed to win the support of more than half of his 303 MPs after 136 Tories rejected the measure and around 40 Tory MPs either did not vote or actively abstained.

Maude told Newsnight on BBC2: "The Conservative party divided roughly like the country does. A lot of people on one side, a lot of people on the other side."

But he added: "Sometimes parts of the Conservative party move but they move more slowly, or a few paces behind the centre of gravity of social attitudes which have changed and will probably continue to change in ways that it is hard to predict. But we get there, maybe at different speeds."

The marriage (same-sex couples) bill will now go to the committee stage in the House of Commons. It will then move to report stage and will then receive a third reading before moving to the House of Lords.